No, because you could still get the silencer off. The funny part about that law is, any paintball/airsoft silencer can be detached somehow, so they all constitute a firearm silencer. Although it doesn't sound like it at a glance, the law effectively bans all silencers, of any type (even those that are purely decorative), on any launcher, even if you have to destroy the thing to get the silencer out.
On the topic of banning pillows, my old school banned elastic bands, because of the potential for them to be used as a weapon (in yet, they didn't ban pencils, pens, or compasses).
